The dependence of photoconducting properties on the thickness of ZnO films deposited on glass substrates by sol-gel spin coating technique has been investigated. The X-ray diffraction (XRD) results indicate that the film with thickness of 260 nm becomes maximum oriented along (002) direction. The field emission scanning electron micrograph (FESEM) shows that the grain size and volume of micropore increases with increase in thickness. Calculation shows that 260 nm film has the highest porosity. The photoconductivity studies exhibit maximum photoresponse for ultraviolet (UV) wavelength (< 400 nm) for the film with 260 mm thickness which is correlated with the microstructural properties of the film. (c) 2006 Elsevier B.V. All rights reserved.